As–Sb–Bi–Au mineralization in the Baogutu gold deposit, Xinjiang, NW China

Here we report the occurrence of some uncommon mineral assemblages including pääkönenite, aurostibite, native arsenic, native antimony, and native bismuth found in the Baogutu gold deposit in the western Junggar, Xinjiang, NW China. The mineralization could be generally subdivided into two types: the gold-bearing quartz-vein type mineralization and disseminated mineralization in the wall rocks. The sulfide minerals in gold lodes commonly include pyrite, arsenopyrite, marcasite, and stibnite. However, the L7 lode in No. 4 orebody and the L1 lode in No. 11 orebody of the Baogutu gold deposit are quite different in terms of their mineral assemblages. The L7 lode contains native arsenic–quartz veins in shallow levels and stibnite–quartz veins at depth. Gold-bearing minerals (electrum, native gold, and rarely aurostibite) mainly coexist with pääkönenite, stibnite, native arsenic, and native antimony. The crystallization of As- and Sb-bearing minerals was likely to have consumed H2S from the hydrothermal fluid, which probably triggered the precipitation of native gold. The L1 lode consists of several discontinuous sulfide-dominated lensoid orebodies. The massive sulfide ores that produced most of the gold resource are characterized by an intimate association between native bismuth and native gold mineralization.